OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2D5A

Reductant Level Sensor A/B Correlation

The signals of the reductant level sensors A and B do not correlate within the calibrated tolerance. One sensor drifts or installation offset between channels.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberD / 5A

Possible causes

  • One sensor characteristic drifted high
  • Harness incorrectly swapped between channels medium

Symptoms

  • Check engine light or NOx warning on
  • AdBlue/DEF level or quality warning
  • Possible no-start countdown after ignore period
  • Failed emissions inspection (NOx)

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 80–350 €
  • Estimated time: 0.3–2 h
  • Component: reductant level sensor a
  • Component: reductant level sensor b
  • Component: scr module
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication